Electron-paramagnetic-resonance identification of silver centers in silicon

Abstract

The observation of silver in silicon by electron paramagnetic resonance (EPR) is reported. In p-type silicon doped with silver, several EPR spectra were detected. Three of these, which are labeled Si-NL42, Si-NL43, and Si-NL44, exhibit hyperfine structure with splitting into two components of equal intensity. The spectrum Si-NL42 with the isotropic Zeeman splitting factor g=1.9744 and an isotropic twofold hyperfine splitting was observed in samples doped with natural silver, as well as in samples doped with silver enriched with one of its isotopes $^{107}\mathrm{Ag}$ and $^{109}\mathrm{Ag}$. The features of the spectrum allow its identification with an isolated interstitial silver atom. The spectra Si-NL43 and Si-NL44 have trigonal symmetry and can be described by an effective electron spin S=1/2 and one nuclear spin I=1/2. With the perpendicular g value nearly 4, the Si-NL44 spectrum can be better analyzed using electron spin S=3/2. By observing an additional twofold splitting in a sample co-doped with $^{57}\mathrm{Fe}$ isotope (I=1/2), the spectrum Si-NL43 is shown to arise from an FeAg pair. From the magnitude of the hyperfine splitting as observed in the samples doped with silver enriched with $^{107}\mathrm{Ag}$ or $^{109}\mathrm{Ag}$ isotopes, all centers are confirmed to be silver related.